1. Field of the Invention
This invention relates to a small junction box which is provided with a branched circuit and a group of fuses disposed in a middle portion of a wire harness, in particular, a wire harness for an automobile.
2. Statement of the Prior Art
For the purpose of convenience of explanation, construction of a conventional junction box body will be explained below with reference to FIG. 5. FIG. 5 shows a cross sectional view of the conventional junction box body.
The junction box body 1 comprises a lower resin cover 2 provided with a plurality of metal bus bars 3 for wiring therein and an upper resin cover 4 mounted on the lower cover 2.
The upper cover 4 is provided with fuse sockets 5 and 6 and a power receptacle 7. Relay terminals 5a, 5b and 6a, 6b are disposed in the fuse sockets 5 and 6 while connecting pins 7a, 7b, 7c and 7d formed by bending distal ends of the bus bars 3 are disposed in the power receptacle 7. The connecting pins 7c and 7d are arranged behind the connecting pins 7a and 7b, respectively, and thus are not shown in FIG. 5.
The relay terminals 5a, 5b and 6a, 6b are electrically connected to the bus bars 3 in the sockets 5 and 6 to form an electric wiring circuit. A wire harness 8 connected to the electric wiring circuit is drawn out of the junction box body 1 and supplies electric power to an emission control computer circuit (hereinafter referred to as "E/C circuit"), as an engine control circuit, through a connector (not shown).
Blade type fuses 5' and 6' of a given standard are attached to the fuse sockets 5 and 6, respectively.
A connector 9 for an ignition switch harness is mounted in the power receptacle 7. A cord 9a secured to the connector 9 is connected to an electric power source such as a battery or the like through an ignition switch (not shown).
However, wire harnesses for automobiles are becoming progressively more complicated in response to an increasing variety of electrical devices provided in automobiles. Accordingly, a simple junction box as mentioned above is insufficient for the above requirements.
In order to meet the above requirements, it is possible to increase the number of junction boxes, if desired. However, this requires greater space, more complicated circuitry, and an increase in production steps. It may also be possible to increase the number of sockets on the junction box or the number of wires taken from the box and to add such fuse sockets in compliance with such additions. However, this makes the junction box itself bulky so that a large space is required to accommodate it and design of the automobile is thus influenced. This is undesirable in that it inhibits the ability to incorporate a large number of devices in an engine compartment as required by current design standards. Accordingly, such a bulky junction box prevents tile utilization of the highly flexible design. Further, a bulky junction box is incompatible with mini-type cars. With the provision of junction boxes having necessary sockets for different kinds of cars, costs rise and manufacturing productivity is adversely affected.
If a junction box having a minimum number of sockets is provided, it is necessary to exchange the first junction box for one having the desired optional sockets when an optional device is incorporated. This is to be an inefficient and costly procedure.